Chandigarh

Firstly, you need to have the documents which prove that you are the only daughter of your parents.

It's not compulsory, however, it depends on the college norms.

B.Sc general courses admission are done through online Centralized Admission process. For more details visit www.dhe.chd.gov.in
Eligibility: - A student who has passed + 2 from State Board/CBSE /ICSE/ or any other recognized Board/ University with 40% aggregate marks shall be eligible to seek admission to BSc Semester I. The admission shall be made on the basis of Punjab University rules.
The cutoff percentage for this college is goes too higher, hence your admission chances are moderate.

Please visit this shiksha.com link on B.Sc in interior designing:
https://www.shiksha.com/design/interior-design/colleges/b-sc-colleges-delhi-ncr

No such course is available. https://www.shiksha.com/college/goswami-ganesh-dutta-s-d-college-chandigarh-22606/courses/bsc-bc.

For this, you can contact to the college authority directly as in my knowledge there is no such provision of getting directly in to the 2nd year of BCA in this university.

Can you please specify the name of the college where you wish to apply?

I hope this link will help you :
https://www.shiksha.com/accounting-commerce/colleges/b-com-colleges-Chandigarh.